G-Whip Returns
Geoff Brown
version is from Franks original G-Whip amateur version which was transformed
by him and SMC into a commercial version. The antenna is based as follows:
Base fibre glass section helically wound and heatshrinked, stainless steel
telescopic adaptor, and 3 whips plus earthing strap, the base is a standard
3/8" fitting for the various mounts available. As standard the antenna is
resonant on 28Mhz with a B/W of about 600 K/cs and no adjustment required,
coils can be added between the base section and the telescopic section,
these coils are currently under production and samples of the complete unit
should be on show at the Newbury Boot sale June 15th. G- Whip was, and still
is, known for it's outstanding performance and not a dummy load antenna! A
dual horizontal version has also been under test and performs very well,
this is very useful for people with limited garden space. Geoff Brown G4ICD
RT
>
> I don't think anyone in their right mind would consider operating HF
> mobile these days,
What's wrong with operating HF mobile ? I work 160M most mornings on the way
to work and have done for many years.
> but if 160m coils are available I would consider
> using the G-whip as a fixed station aerial for Top Band
If you have room to string out 22-25M of wire then a suitable impedance
matching device that will work with the limited ATU in most modern radio's
will work much better than any mobile whip. I use a T200-2 toroid ring wound
with 14 turns of twin enamel wire housed in a water proof PVC box at one end
and it tunes and works very well on 160M, a bit touchy on 80M and ok on 40M.
It does tune up ok on the higher HF bands but my nest of dipoles work better
for 20-10M.
> It's certainly a cut above the "Miracle Whip" and even magnetic loops!
That's for sure.
:-)
Alt Beer
"Walt Davidson" <g3...@despammed.com> wrote in message
news:389d349h6f7eqb9jj...@4ax.com...
> I don't think anyone in their right mind would consider operating HF
> using the G-whip as a fixed station aerial for Top Band (with a
> suitable counterpoise) and maybe for higher frequency bands as well.
> It's certainly a cut above the "Miracle Whip" and even magnetic loops!
>
> Walt Davidson Email: g3nyy @despammed.com
You should get out more.... may be with a Joystick VFA :-)
Geoff Brown
for a decent HF mobile whip, not like all the 50 ohm loads around these days!
BTW, just had the gud old Chemo/Radio, but all ok now, 18 months of h...
GB
damaged with issues .........
had over the years .......
Theo
"RT" <nos...@reject.com> wrote in message
news:g16aha$2hu7$1...@energise.enta.net...
>
> >
> > I don't think anyone in their right mind would consider operating HF
> > mobile these days,
>
> What's wrong with operating HF mobile ? I work 160M most mornings on the
way
> to work and have done for many years.
I agree, IMHO there should be more HF mobile operation, not less.
Also, let's get back to the good old days of mobile rallies and picnics,
before they degenerated into greedy money-making computer fairs!
Spike
Theo wrote:
>
>"RT" <nos...@reject.com> wrote in message
>news:g16aha$2hu7$1...@energise.enta.net...
>>
>> WAFD wrote:
>>
>> > I don't think anyone in their right mind would consider operating HF
>> > mobile these days,
You got a bite on that one...
>> What's wrong with operating HF mobile ? I work 160M most mornings on the
>> way to work and have done for many years.
>
> I agree, IMHO there should be more HF mobile operation, not less.
> Also, let's get back to the good old days of mobile rallies and picnics,
> before they degenerated into greedy money-making computer fairs!
>
Just had one of those at Dunstable Downs :-)
--
from
Aero Spike
SteveE
Hi Geoff
Good luck with the whip project.
I am a little bemused though at your links to what is just an internet
portal of what is on here, in fact stuff taken from here in its entirety.
Unless I am missing something obvious, I can't see any benefit that this
website offers if there is any over USENET, or even Google groups.
Can you explain?
Steve
Brian Morrison
> On Fri, 23 May 2008 12:40:08 +0100, "RT" <nos...@reject.com> wrote:
>
>>> I don't think anyone in their right mind would consider operating HF
>>> mobile these days,
>> What's wrong with operating HF mobile ? I work 160M most mornings on the way
>> to work and have done for many years.
>
> soon will be.) If a police officer thinks you are not in full control
> of your vehicle, then it is already.
And has been for many years, so if the police wish to take action they can.
--
Brian
NikTheGeek
Pity there wasn't a url for more info. I could do with a new HF mobile
antenna...
--
My:d1Ck.isbig:eno.ugh%w1th0ut.y0U/spaMMErs.trY1ng:to.sEll%me-p1LLs!
JM
"Geoff Brown" <goa...@spam.co.uk> wrote in message
news:f4d17400a43d4c3a...@newspe.com...
> The good old G-Whip mobile antenna returns, this time with WARC bands,
> this
> version is from Franks original G-Whip amateur version which was
> transformed
> G4ICD
>
> url:http://myreader.co.uk/gp/1404-1.aspx
Hi,
I still have a full set of G Whips.
80/40 coils
and the Top section for 20/15.
I did talk to Frank on the phone some years ago regarding a 17 metre top.
But it was not available.
But I saw a 20 metre top section at a rally for 50p. Its now on 17.
They work very well.
One question. About 25 yeas ago I was kind of coasting up the A1M from
Leicester Rally.
With TS120 on 20 metres.
I lost all signals and as it happened the PA transistors.
The G Whip had snapped at its base.
I had visions of some driver with a G whip pinning him to the seat.
Never did find it.
Often wondered where it ended up.
de Johnny G3LIV
Theo
> It's anti-social, dangerous and should be made illegal. (It probably
> soon will be.) If a police officer thinks you are not in full control
> of your vehicle, then it is already.
So is smoking, using a mobile phone, and women putting on makeup whilst
driving,
and sod all is being done to stop those activities, so what chance has
mobile radio operating
have of getting banned?
RT
Day-Glo Wally dribbled..........
>>> I don't think anyone in their right mind would consider operating HF
>>> mobile these days,
>>
>>What's wrong with operating HF mobile ? I work 160M most mornings on the
>>way
>>to work and have done for many years.
>
> will be.)
It is no more anti social than locking yourself away in another room or in a
old shed in the garden away from your family and it's far less dangerous
than carrying on a conversation with a passenger when driving.
> If a police officer thinks you are not in full control
> of your vehicle, then it is already.
>
There are current laws to deal with dangerous drivers, we don't need another
Nanny State law called for by namby pamby spineless stupid people who like
to blame others for their own stupidity.
No, I will not give up my freedoms just because of "IF"
RT
>>>> I don't think anyone in their right mind would consider operating HF
>>>> mobile these days,
>>> What's wrong with operating HF mobile ? I work 160M most mornings on the
>>> way
>>> to work and have done for many years.
>>
>> It's anti-social, dangerous and should be made illegal. (It probably
>> soon will be.) If a police officer thinks you are not in full control
>> of your vehicle, then it is already.
>
> And has been for many years, so if the police wish to take action they
> can.
>
Exactly, just because the Day-Glo Derricks of this world can't multi task
then they should impose their will on other who are capable.
If some is using a mobile phone or a two-way radio and is driving
dangerously then the Police can take action without a stupid blanket bans by
the Nanny State.
RT
<snip>
> but if 160m coils are available I would consider
> using the G-whip as a fixed station aerial for Top Band (with a
> suitable counterpoise) and maybe for higher frequency bands as well.
Been there, done it and got the T-shirt so don't waste your money, unless
you have a window box for a garden then a random length of wire with a good
ATU will outperform any HF mobile whip.
LVN
"SteveE" <st...@nospamforme.co.uk> wrote in message
news:4xBZj.8281$DZ6....@text.news.virginmedia.com...
>
>
> I am a little bemused though at your links to what is just an internet
> portal of what is on here, in fact stuff taken from here in its entirety.
>
> Unless I am missing something obvious, I can't see any benefit that this
> website offers if there is any over USENET, or even Google groups.
>
> Can you explain?
>
LVN
>
>
> If some is using a mobile phone or a two-way radio and is driving
> dangerously then the Police can take action without a stupid blanket bans
> by the Nanny State.
>
driving ban bill. Chiefly because it's simplex.
Police can still do you for driving without due care, but I guess it's
unlikely - tytpically people just chuck the mic on the floor when necessary
MB
"Brian Morrison" <scra...@fenrir.org.uk> wrote in message
news:g16p9r$gv8$1...@news.datemas.de...
> Walt Davidson wrote:
>> On Fri, 23 May 2008 12:40:08 +0100, "RT" <nos...@reject.com> wrote:
>>
>>>> I don't think anyone in their right mind would consider operating HF
>>>> mobile these days,
>>> What's wrong with operating HF mobile ? I work 160M most mornings on
>>> the way
>>> to work and have done for many years.
>>
>> It's anti-social, dangerous and should be made illegal. (It probably
>> soon will be.) If a police officer thinks you are not in full control
>> of your vehicle, then it is already.
>
>
Unlike the police themselves who drive around using their AIRWAVE radios -
one was shown on BBC1's Traffic Cops using two radio/phone whilst involved
in a high speed chase. At the same time they are often also playing with a
whole range of extra equipment in their cars.
Ian Jackson
<gareth...@gmail.com> writes
Those who don't are providing a perfect excuse for the do-gooders to get
amateur mobile operation banned. I started operating /M in 1960, and
have always used handsfree.
--
Ian
RT
>>There are current laws to deal with dangerous drivers, we don't need
>>another
>>Nanny State law called for by namby pamby spineless stupid people who like
>>to blame others for their own stupidity.
>>
>>No, I will not give up my freedoms just because of "IF"
>
>
Only "IF" I drive dangerously.
RT
>
> DILLIGAF what you've done or how many T-shirts you've got?
^^^^^^^^
What ?
Duncan Munro
class_a
RT
> ITYF it will be for you to prove that you did not. In this country,
> you are guilty until proven innocent.
>
Can't argue with that.
Spike
Walt Davidson wrote:
>On Sat, 24 May 2008 13:54:24 +0100, "RT" <nos...@reject.com> wrote:
>
>>>>No, I will not give up my freedoms just because of "IF"
>>>
>>> You will when you get 6 points on your licence.
>>>
>>
>>Only "IF" I drive dangerously.
>
>ITYF it will be for you to prove that you did not. In this country,
>you are guilty until proven innocent.
>
>73 de G3NYY
I see you are still taking the 'Assistant Chief Constable of
Leicestershire' line. To refresh your memory, he didn't seem to know
how things worked either, only that time he was talking about bladed
objects being carried in public.
--
from
Aero Spike
twizzle
>
>
>> ITYF it will be for you to prove that you did not. In this country,
>> you are guilty until proven innocent.
>>
>
> Can't argue with that.
>
>
>
Steve Terry
> On Sat, 24 May 2008 17:36:02 +0100, Spike <Aero.Spike@S&T.invalid>
> wrote:
>
>>I see you are still taking the 'Assistant Chief Constable of
>>Leicestershire' line. To refresh your memory, he didn't seem to know
>>how things worked either, only that time he was talking about bladed
>>objects being carried in public.
>
> a feature on the TV news about police in London now stopping people in
> the street at random and searching them for knives, and setting up
> portable "knife arches" to scan people for hidden knives.
> 73 de G3NYY
> Walt Davidson
>
I carry a miniature Stanley knife box cutter on my key chain,
how many years will get for carrying that?
and will I have to start wearing hoodies to match my new criminal status?
In France you can buy any flick knife, etc. you like.
Bloody fools still assume intention matters.
Steve Terry
Jimbo's Radio Shack and workshop ....
>and possibly
> because the like pratting around making out they're unmarked
> police-cars to other car-drivers..
>
> Nick.
Cbrs used to think I was the Busby in 1979....and take off at high speed
.........
Graham M0YSU
message news:3Gx_j.62333$UP6....@newsfe14.ams2...
More like they knew you Jim and didn't want to get involved... ;)
--
73
Graham
-- ----- -.-- ... ..-
Graham M0YSU
news:f26l3411iq9coqse4...@4ax.com...
> On Sat, 24 May 2008 19:23:48 +0100, "Steve Terry" <gFOU...@tesco.net>
> wrote:
>
>>I carry a miniature Stanley knife box cutter on my key chain,
>>how many years will get for carrying that?
>
> metal detectors (Now there's a surprise).
>
> Nick.
They do if you do the Birmingham thing and put lots of nails in at the end
:o)
Steve Terry
<luc...@eternal-flames.gov> wrote in message
news:f26l3411iq9coqse4...@4ax.com...
> On Sat, 24 May 2008 19:23:48 +0100, "Steve Terry" <gFOU...@tesco.net>
> wrote:
>
>>how many years will get for carrying that?
>
> metal detectors (Now there's a surprise).
> Nick.
>
and wouldn't I have trouble getting it into my pocket
Steve Terry
Steve Terry
<luc...@eternal-flames.gov> wrote in message
news:88nl34h39l7387oom...@4ax.com...
> On Mon, 26 May 2008 15:55:21 +0100, "Steve Terry" <gFOU...@tesco.net>
> wrote:
>>How do I attach a wooden Baseball bat to my keychain?
>>and wouldn't I have trouble getting it into my pocket
>>Steve Terry
>
>
> With a 'key-fob' the size of a baseball-bat, you'd never have to worry
> about losing your keys again.
>
> The bat being wooden, means that even if you drop your keys over the
> side of a boat, the key-fob will float
>
> As for it not fitting in your pocket... Get a lanyard and hang it
> around your neck.
> Nick.
>
I might as well have a sign saying "Arrest me" around my neck as well
Steve Terry
Jim GM4DHJ...........
"Graham M0YSU" <m0...@yahoo.com> wrote in message
news:483acf68$0$30635$834e...@reader.greatnowhere.com...
Jimbo's Radio Shack and workshop ....
> > Cbrs used to think I was the Busby in 1979....and take off at high speed
>
> More like they knew you Jim and didn't want to get involved... ;)
>
didn't want to get caught more like ... never saw a MK1 Capri go so fast
....
Graham M0YSU
news:qanl34poa3rg150gg...@4ax.com...
> On Mon, 26 May 2008 15:56:37 +0100, "Graham M0YSU" <m0...@yahoo.com>
> wrote:
>
>
>>
>>They do if you do the Birmingham thing and put lots of nails in at the end
>>:o)
>
>
> Nick.
Very carefully ;)
serendi...@googlemail.com
> There is no such need for radio amateurs to use radios in their cars.
It could be said there is no need for amateur radio.
There is a world of difference between driving in built-up area in
high traffic density with lots of vehicle manoeuvres, (where full
concentration is obviously required), and driving in rural area/quiet
road/dual carriageway/motorway, where there are no pedestrians and
fewer vehicles. If it were necessary to use two hands to drive a
vehicle safely, then people with the use of only one arm would not be
allowed to drive.
What really concerns me is the profileration of dash mounted car
radios with pop-up tv screens built in. And people sending text
messages whilst driving. I see that every day on the A1. Its far more
dangerous than holding a phone to your ear and talking whilst still
looking at the road ahead.
73, Chris
G4FZN
Spike
Walt Davidson wrote:
>On Tue, 27 May 2008 21:30:30 -0700 (PDT),
>serendi...@googlemail.com wrote:
>
>>What really concerns me is the profileration of dash mounted car
>>radios with pop-up tv screens built in.
>
>They will be banning the use of sat-nav devices next.
>
>73 de Wlat
That has already been proposed.
Not for safety reasons, but because drivers have been using SatNav
track logs to prove they weren't speeding, when the police
radar/laser/'safety' camera said they were. The police don't like it.
Still, if you have nothing to hide, you have nothing to fear.
--
from
Aero Spike
Brian Reay
news:ob6q34ps9oqtfsj6n...@4ax.com...
>
> That has already been proposed.
>
> Not for safety reasons, but because drivers have been using SatNav
> track logs to prove they weren't speeding, when the police
> radar/laser/'safety' camera said they were. The police don't like it.
Can you cite cases where this has happened?
--
73
Brian, G8OSN
www.g8osn.org.uk
Da...@nothere.com
Cannot remember the exact details but it was all over the news a few weeks
back. A quick google would find it.
And another just about Christmas time.
Dave
Spike
Brian Morrison
>> They will be banning the use of sat-nav devices next.
>
> That has already been proposed.
>
> Not for safety reasons, but because drivers have been using SatNav
> track logs to prove they weren't speeding, when the police
> radar/laser/'safety' camera said they were. The police don't like it.
>
> Still, if you have nothing to hide, you have nothing to fear.
This is insane, effectively it says that knowing where you are and how
fast you are travelling will be illegal.
Presumably the next step will be to remove speedometers from cars entirely?
--
Brian
class_a
>> radios with pop-up tv screens built in.
>
I consider satnav to be a safety feature!! If I'm in an area I don't
know, instead of being distracted looking for road signs to see where I
should be going, I just follow the audible directions from my satnav.
This allows me to concentrate much more on the traffic and not where the
next junction is that I need to take.
Spike
Brian Morrison wrote:
>Spike wrote:
>
>>> They will be banning the use of sat-nav devices next.
>>
>> That has already been proposed.
>>
>> Not for safety reasons, but because drivers have been using SatNav
>> track logs to prove they weren't speeding, when the police
>> radar/laser/'safety' camera said they were. The police don't like it.
>>
>> Still, if you have nothing to hide, you have nothing to fear.
>
>This is insane, effectively it says that knowing where you are and how
>fast you are travelling will be illegal.
Not strictly so.
They want to get rid of the law they wrote to make such devices not
fall under the 'TV in a car' law that's been around for decades. Ergo,
you wouldn't be able to view it legally.
Nothing to stop you sticking it on a side window behind the driver,
and letting Fiona's honeyed voice guide you.
Besides, look at this:
And this:
http://www.storagedepot.co.uk/Handheld-GPS/sc893/p74.aspx
This looks interesting, as it can be reconfigured to give a wide
variety of readouts - perhaps such as peak speed in the last mile,
half mile, quarter mile, 220 yds, 110 yds.....just to show the nice
officer....
>Presumably the next step will be to remove speedometers from cars entirely?
LOL.
They tried to ban breathalysers in pubs for much the same reason.
--
from
Aero Spike
Brian Reay
Oh, so it is the California police you were referring to.
It also seems it is the driver who is "was apparently none too pleased with
the device".
The police seem to have commented on the accuracy of the speed from the GPS,
which is a legitimate comment. Unless something has changed, GPS units
derive speed by comparing changes in position and time- effectively a
differentiation (delta position / delta time). I assume you know the
problems associated with using differentiation on measurements?
Brian Morrison
> "Spike" <Aero.Spike@S&T.invalid> wrote in message
> news:inbq341e7elvf3nrc...@4ax.com...
>> Brian Reay wrote:
>>
>>> "Spike" <Aero.Spike@S&T.invalid> wrote in message
>>> news:ob6q34ps9oqtfsj6n...@4ax.com...
>>>> That has already been proposed.
>>>>
>>>> Not for safety reasons, but because drivers have been using SatNav
>>>> track logs to prove they weren't speeding, when the police
>>>> radar/laser/'safety' camera said they were. The police don't like it.
>>> Can you cite cases where this has happened?
>> http://www.theregister.co.uk/2007/10/26/gps_speeding_challenge/
>>
>
> Oh, so it is the California police you were referring to.
>
> It also seems it is the driver who is "was apparently none too pleased with
> the device".
>
> The police seem to have commented on the accuracy of the speed from the GPS,
> which is a legitimate comment. Unless something has changed, GPS units
> derive speed by comparing changes in position and time- effectively a
> differentiation (delta position / delta time). I assume you know the
> problems associated with using differentiation on measurements?
Yes, but you'll find that actually when locked to 4 or more SVs, most
GPS receivers use the doppler frequency of the SVs to derive speed. All
three of the receivers I have quote their accuracy as 1 LSB of the
displayed speed which is 0.1mph.
--
Brian
Gerry
> Oh, so it is the California police you were referring to.
>
> It also seems it is the driver who is "was apparently none too pleased with
> the device".
>
> The police seem to have commented on the accuracy of the speed from the GPS,
> which is a legitimate comment. Unless something has changed, GPS units
> derive speed by comparing changes in position and time- effectively a
> differentiation (delta position / delta time). I assume you know the
> problems associated with using differentiation on measurements?
Did you read the comments??
http://www.theregister.co.uk/2007/10/26/gps_speeding_challenge/comments/#c_84872
Gerry ....
Matthew Haigh
> This is insane, effectively it says that knowing where you are and how
> fast you are travelling will be illegal.
Perhaps you need to have a chat to Heisenberg about that.
Brian Morrison
As you will know Matt, having met me, there's no way I'm small enough
for quantum effects to have a bearing!
--
Brian
Spike
Brian Reay wrote:
>"Spike" <Aero.Spike@S&T.invalid> wrote in message
>news:inbq341e7elvf3nrc...@4ax.com...
>>
>> Brian Reay wrote:
>>
>>>"Spike" <Aero.Spike@S&T.invalid> wrote in message
>>>news:ob6q34ps9oqtfsj6n...@4ax.com...
>>> >
>>>> That has already been proposed.
>>>>
>>>> Not for safety reasons, but because drivers have been using SatNav
>>>> track logs to prove they weren't speeding, when the police
>>>> radar/laser/'safety' camera said they were. The police don't like it.
>>>
>>>Can you cite cases where this has happened?
>>
>> http://www.theregister.co.uk/2007/10/26/gps_speeding_challenge/
>>
>
>Oh, so it is the California police you were referring to.
The cases I had in mind were in the UK; I couldn't quickly find them
on Google, although I thought they were in the last year and took
place somewhere in Kent. The Californian one was a sample, although I
didn't limit myself to UK cases in my OP.
The first elephant in the room here is that the UK police can see the
implications for their own systems, procedures, and modus operandi.
>It also seems it is the driver who is "was apparently none too pleased with
>the device".
Nice bit of disingenuity....the end of the immediately preceding
sentence was "...so his mother and stepdad Roger Rude - himself a
retired police deputy - decided to fit his car with a GPS which
"monitors the location and speed" of the Japanese wheels...."
It wasn't the device that he was none-too-pleased with. It was having
it fitted by his parents - a whole different ball-game for a teenager.
>The police seem to have commented on the accuracy of the speed from the GPS,
>which is a legitimate comment.
The second elephant in the room is that the GPS device seem to offer
evidence for comment on the accuracy of the police's equipment, which
is also a legitimate comment.
> Unless something has changed, GPS units
>derive speed by comparing changes in position and time- effectively a
>differentiation (delta position / delta time). I assume you know the
>problems associated with using differentiation on measurements?
The third elephant in the room.....
Once locked on, the GPS uses dopper to determine speed.
You can google yourself for cites.
--
from
Aero Spike
Da...@nothere.com
>The cases I had in mind were in the UK;
I think one of the cases was to do with the GPS units being offered by
insurance companies for "young" drivers. It proved that the driver was doing
under 30mph when the hand held police laser clocked the driver at 40+
Spike
Spike wrote:
This is more along the lines of my memory:
"This just happened in the UK too
By jon
Posted Friday 26th October 2007 11:27 GMT
An inventor caught by kent police for apparently doing over 40 in a 30
zone presented evidence from a GPS product he was testing which showed
his true speed to be 29.7mph.
Kent police have now suspended use of speed guns pending
investigations."
And a little further down...although I can't verify this immediately:
"But didn't get to court
By Martin
Posted Friday 26th October 2007 11:57 GMT
Go
Didn't he get off because the plod in question had retired so it
didn;t even reach court."
http://www.theregister.co.uk/2007/10/26/gps_speeding_challenge/comments/
The latter comment suggests why no more has been heard on the topic.
--
from
Aero Spike
Catweazel
> On Tue, 27 May 2008 21:30:30 -0700 (PDT),
>
> >What really concerns me is the profileration of dash mounted car
> >radios with pop-up tv screens built in.
>
>
Don't get me started on this one - every now and then on the way to
work I fetch up behind someone piddling along - and guess what: each
time I see the white glow of a sat nav screen and the driver's head
held inclined toward it rather than the road. I suppose it could be
worse - a driver reading the paper or a female composing a text
message both which I've also seen on the M1.
Brian Reay
"Spike" <Aero.Spike@S&T.invalid> wrote in message
>> Unless something has changed, GPS units
>>derive speed by comparing changes in position and time- effectively a
>>differentiation (delta position / delta time). I assume you know the
>>problems associated with using differentiation on measurements?
>
> The third elephant in the room.....
>
> Once locked on, the GPS uses dopper to determine speed.
>
As I said "unless something has changed". I will elucidate.
The RX is given a "preset" set of SV data- inc. approx. SV position and
Doppler (I can't recall if the latter is given directly or as a velocity to
permit local calculation of Doppler.) However, having "locked on" (to use
your phrase), the RX LO can be tracked to find the relative change in SV to
rx velocity but this doesn't "fix" any original error in the estimate (more
simply, with both moving how do you know which one changed its velocity to
cause a change in the Doppler shift. With a large (relative) velocity
difference and the majority of the absolute velocity being associated with
the SV, the error budget would be a tad biased).
GPS does not use Doppler to find position, it is a triangulation technique
based in distance measurement. The older Transit system did use Doppler but
that is probably now defunct- it was already being phased out when I was
working on "NavStar" augmented systems in the mid 80s. As I recall, it did
last a bit longer than planned (I think due to problems getting the GPS
constellations "complete").
Dave
> The police seem to have commented on the accuracy of the speed from the GPS,
> which is a legitimate comment. Unless something has changed, GPS units
> derive speed by comparing changes in position and time- effectively a
> differentiation (delta position / delta time). I assume you know the
> problems associated with using differentiation on measurements?
What you are saying here, Brian, is that GPS is not to be trusted for speed.
My last 4 cars have all shown an inaccuracy at all levels of speed
according to my very old GPS system. The worst told me that I was
driving at 35 MPH when both my GPS and a police speed monitoring trailer
said I was doing 29 MPH. This inaccuracy gets worse, the faster you
drive. In one car, I could quite happily drive at an indicated speed of
85 MPH and not be bothered by the police. Indeed, I passed one at an
indicated speed of 95 MPH and he never batted an eye. (End of shift
syndrome? I'll never know)
Dave
Spike
Brian Reay wrote:
>The RX is given a "preset" set of SV data- inc. approx. SV position and
>Doppler (I can't recall if the latter is given directly or as a velocity to
>permit local calculation of Doppler.) However, having "locked on" (to use
>your phrase), the RX LO can be tracked to find the relative change in SV to
>rx velocity but this doesn't "fix" any original error in the estimate (more
>simply, with both moving how do you know which one changed its velocity to
>cause a change in the Doppler shift. With a large (relative) velocity
>difference and the majority of the absolute velocity being associated with
>the SV, the error budget would be a tad biased).
This isn't my technical area, but the explanation above seems to lack
something. Are you saying that a GPS locks on to a single signal, for
which there will be an understandable error, and that error is never
minimised or corrected by processing the other signals received?
That doesn't sound right.
Any error is going to cancel out over a period of time, probably
determined by the computing power of the receiver. But once having
done so, by calculating a form of datum for which all the errors are
minimised should lead to e.g. a velocity determination that was
correct to a certain level - perhaps < 0.1 mph as that seems to be the
resolution of most civilian GPS devices.
>GPS does not use Doppler to find position
No-one suggested it did.
--
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paul welford
paul welford
Johnny Melvin
"paul welford" <baz...@yahoo.co.uk> wrote in message
news:c4f1ea75b2d14f0e...@newspe.com...
I still have a set of G Whips.
I purchased them circa 1974 or so.
I wonder if they are still under warranty Lol.
They still hold there own against the PRO-AM and YAESU
I have.
de Johnny G3LIV